What are you running regarding mods and what year?
Top Speed numbers for Gen 2. What are you getting?
- Thread starter 1badmax
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Traumahawk
Well-Known Member
Just remember that the Gen 2 speedo is roughly 7% off.....as in it reads too fast. On my speedo healer, I had to put in 6.7% to get it to read accurate.
All bike speedometers are off and mostly reading higher than actual speed. . Some more than others. My 175 on speedometer would probably GPS @ 166-168 just guessing. Mine is a little closer with the taller tire. Plus the faster you go the further off it gets.
2017VMax
Well-Known Member
That's ok considering you are comparing your speed to every one else with a speedometer
Not sure who this was meant for, if is was me my original quote "I realize is not totally accurate since it's just off the speedometer and I did not have my GPS with me."That's ok considering you are comparing your speed to every one else with a speedometer
I'm not sure I can agree with that. The only meaningful comparison is percentage and since the aspect ratio is a percentage of the width, this translates into a percentage difference in diameter(circumference). I haven't done the calculations but my gut tells me it will result in same percentage inaccuracy shown on the speedo i.e. the smaller tyre will be off by the same percentage as the larger tyre.
Someone with more of a mechanical engineering background may be able to settle this, but when I said, "I agree (with 1badmax)," what I meant is that a difference in height of the wheel/tire affects by a larger margin the speed capability of the bike, say on top-end. I just posted on another thread, about Gen. 1 replacement tires, that when you switch to a 17" or 18" wheel/tire combo, and the shorter-height sidewall of the sportbike 50, 55, or 60 series aspect ratios, result in a lower height wheel/tire combo when compared to a Gen. 1 OEM 90-series wheel/tire; this lowers your top-speed achievable, and a taller wheel/tire will result in a higher top-speed than a shorter wheel/tire overall height. That is to say, a 17" 50-series tire will have an overall height which is shorter than an 18" 50-series wheel/tire combo. The distance travelled by one complete revolution of the 17" wheel/tire is less-than the distance travelled by one complete revolution of an 18" wheel/tire. Therefore, as I understand it, the disparity of displayed speed to actual, timed speed would be greater for the smaller-diameter wheel/tire combo. Does the gearing in the mechanical speedometer sending unit change, because of a difference in wheel/tire size? Obviously-not, but the effective speed displayed and its margin of error is greater for the 17" wheel/tire, than it is for the 18" wheel/tire.
arggghhhhhh please please FM, don't make me do the calculations. I stick by what I said the percentage disparity in speedo reading is the same.
Let's say the speedo overreads by 10%. At 30 mph it will show 33 mph and at 70 mph it shows 77 mph. So it overreads by 3 and 7 mph respectively yet the percentage is same. To say the speedo is less accurate at 70 mph as it is out by 4 mph more than it is at 30 mph is not meaningful, which is how I interpreted the original comment.
Let's say the speedo overreads by 10%. At 30 mph it will show 33 mph and at 70 mph it shows 77 mph. So it overreads by 3 and 7 mph respectively yet the percentage is same. To say the speedo is less accurate at 70 mph as it is out by 4 mph more than it is at 30 mph is not meaningful, which is how I interpreted the original comment.
OK yes, I agree with what you say, my interpretation of the discussion is that for different wheel/tire diameters/heights, there is a larger % difference between shorter and taller ones. You're referring to the differences at-speed for a single wheel/tire, I'm referring-to differences between different height wheel/tire combinations.
You can see the light but you run through it so quick it didn't matter. LOL
And did the Roy Orbison 45 finish by the time you got back to the cafe?
Speed is relative. One of my brothers had an XK120 drophead coupe and a roadster (roadster: clip-in windows, drophead coupe, a convertible with roll-up windows). Back in the 1960's, he went into the service, and asked us to sell it for him, he said, "if I make it through this, I'll buy another one when I'm out." Another brother and I took it to a long lonesome road and got it up to nearly 120 mph before we decided "ok, that's fast-enough!" The drum brakes faded as we approached an intersection, and we barely got it stopped. That was the fastest this teenager had been to that point. Watching the Jaeger white needle spin around the MPH markings as the tach slowly climbed towards redline was a great thrill for this youngster. Trying to bring the Jaguar to a halt was a thrill of a different nature.
At this stage of my life, I'd rather live to a 'ripe old age,' as long as I remain in good health and my need for speed isn't much of a motivation these days. However, I do enjoy seeing the red light on the dash flicker, and acceleration of a VMax is still a thrill.
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Woody
Well-Known Member
I love using that red gen1factory shift light.
